1. Field of the Invention
The present invention relates to a numerical control system comprising a plurality of systems having their control periods different from one another.
2. Description of the Related Art
As a numerical control apparatus in recent years, there is one which includes a control system for controlling a machine as a main function of the numerical control apparatus, and an operating system for providing an input/output function to produce programs, to set parameters, and to set tool data for operation of a machine tool, wherein these systems function in association with each other as a numerical control system (see, for example, a first patent document: Japanese patent application laid-open No. 2002-108423).
In such a numerical control system, data transfer (sending and receiving) is carried out between the two systems. In the above-mentioned first patent document, a control unit for controlling the machine and a operation panel arranged outside of the control unit are electrically connected to each other, and if a processing request issued from the control unit is not received by the operation panel, it is assumed that abnormality occurs.
However, conventionally, a numerical control apparatus is provided with a collision prevention function to prevent collisions between parts of a machine, tools, jigs and materials by checking shape data thereof by means of a computer (see, for example, a second patent document: Japanese patent application laid-open No. H5-8,152).
Collision checks have been performed in the past by using the shapes in the two-dimensional plane of the machine parts, tools, jigs and materials, but in recent years, such checks are being made by using three-dimensional shape data (see, for example, a third patent document: Japanese patent application laid-open No. H9-230,918).
However, in the numerical control apparatus as described in the above-mentioned first patent document, whether the operation panel receives a signal is only used as a criterion for determination, so there is a problem that only a system malfunction can be determined.
In addition, in the above-mentioned numerical control system as described in the second patent document, the more precisely a real machine is tried to be expressed so as to perform collision detection with high accuracy by using three-dimensional shapes, the more processing time is required, and in that case, there will be a problem of inducing a system malfunction.
Further, if the system falls into a state in which a lot of processing time for collision detection is required in case where a tool and a material are in contact with each other, there is a problem that a work to be processed might be damaged or the tool might be broken.